[llvm] r244455 - Modify r244405 to clearer code, per David Blaikie suggestion.

[David Blaikie via llvm-commits]

On Mon, Aug 10, 2015 at 9:56 AM, Yaron Keren <yaron.keren at gmail.com> wrote:

> Oops, I didn't notice that additional change when editing and did not copy
> & paste.
> Fixed + added comment in r244461.
>

It's still pretty easy to roll the two expressions in together (the comment
helps, for sure - though it's easy to gloss over them). Doing all the
variable initialization on the local, rather than in the vector, would
separate the local creation from the push_back a lot & make this probably
fine without a comment, I think.

- David


>
>
> 2015-08-10 19:46 GMT+03:00 David Blaikie <dblaikie at gmail.com>:
>
>>
>>
>> On Mon, Aug 10, 2015 at 9:15 AM, Yaron Keren via llvm-commits <
>> llvm-commits at lists.llvm.org> wrote:
>>
>>> Author: yrnkrn
>>> Date: Mon Aug 10 11:15:51 2015
>>> New Revision: 244455
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=244455&view=rev
>>> Log:
>>> Modify r244405 to clearer code, per David Blaikie suggestion.
>>>
>>>
>>> Modified:
>>>     llvm/trunk/tools/dsymutil/DwarfLinker.cpp
>>>
>>> Modified: llvm/trunk/tools/dsymutil/DwarfLinker.cpp
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/dsymutil/DwarfLinker.cpp?rev=244455&r1=244454&r2=244455&view=diff
>>>
>>> ==============================================================================
>>> --- llvm/trunk/tools/dsymutil/DwarfLinker.cpp (original)
>>> +++ llvm/trunk/tools/dsymutil/DwarfLinker.cpp Mon Aug 10 11:15:51 2015
>>> @@ -2884,8 +2884,8 @@ void DwarfLinker::patchLineTableForUnit(
>>>        if (StopAddress != -1ULL && !Seq.empty()) {
>>>          // Insert end sequence row with the computed end address, but
>>>          // the same line as the previous one.
>>> -        Seq.reserve(Seq.size() + 1);
>>> -        Seq.emplace_back(Seq.back());
>>> +        auto NextLine = Seq.back();
>>> +        Seq.emplace_back(NextLine);
>>>
>>
>> I don't think there's any benefit to emplace_back here since there are no
>> explicit conversions required. I'd probably usse push_back - and this still
>> seems like it'd be easy for someone to just decide to fold the two
>> statements together & create the original bug. The suggestion I was making
>> was to avoid doing the initialization (the following several assignment
>> statements \/ ) on the container element itself, but do it on the local.
>> Then push that local onto the sequence - that seems less subtle (or at
>> least it hides it better by not making it look like a trivial cleanup to
>> collapse two expressions would be an improvement).
>>
>>
>>>          Seq.back().Address = StopAddress;
>>>          Seq.back().EndSequence = 1;
>>>          Seq.back().PrologueEnd = 0;
>>>
>>>
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>>>
>>
>>
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